The present invention relates to an automatic embossing device and method for plastic floor tile, especially to an automatic embossing device and method with characteristics of .higher accuracy, greater stability, and better production efficiency for plastic floor tile.
The plastic floor tile is formed by bonding a base substratum, an intermediate laminar, and a printed tape. A layer of thin tape or thick tape can be further attached. In order to exhibit the modeling of the printed pattern on the tape, an embossing process is needed. The conventional embossing process uses an encoder to sense the supply speed of printed tape and uses a computer to compare the speed of the pressing wheel (or the bonding wheel) for synchronously controlling the embossing process. Moreover, a position sensor is used to sense the position mark on the printed tape. When the sensed cumulative error exceeds a certain quantity, a breaking or decelerating action is done to stretch the tape for performing a postponed adjustment process.
The polyvinyl chloride (PVC) tape is generally adopted as the printed tape in the conventional automatic embossing technology for the plastic floor tile. Because the PVC tape will soften when heated (exceeding the transition temperature of the plastic glass) before it enters the pressing wheel of high temperature, the stretching strength of the tape will substantially reduced, resulting in unstable supply speed of the tape. Although a servomotor can be used to drive the supply wheel, the relation between the speed of the supply wheel and that of the pressing wheel is not linear such that the error will be large. Fast and stable embossing can not be achieved only using this kind of speed comparison for control. Furthermore, pressing wrinkle or even break can easily arise from the looseness of the tape. Because the error of the embossing is large, the production efficiency can not be increased.
Accordingly, the primary object of the present invention is to provide an automatic embossing device and method for plastic floor tile, which can eliminate the drawbacks of only using the pressing wheel to unstably drive the supply wheel in prior art. The present invention can steadily control the supply quantity and the unwinding tension of the tape such that no pressing wrinkle or break can arise. The accuracy and stability of the embossing are also increased.
Another object of the present invention is to provide an automatic embossing device and method for plastic floor tile, wherein selection flexibility of material of the printed tape can be increased. Even material of lower stretching strength can be adopted.
Yet another object of the present invention is to provide an automatic embossing device and method for plastic floor tile, which can calculate out the speed compensation of the rotation speed of the supply control wheel using a computer. Because the speed compensation is small and instant, higher accuracy and stable rotation can be achieved.
The various objects and advantages of the present invention will be more readily understood from the following detailed description when read in conjunction with the appended drawing, in which: